I. Field of the Invention
The present invention relates to a medical device which blindly and selectively facilitates the rapid, gentle and accurate guiding, aiming, and stabilizing of tubular or elongated members relative to the larynx and esophagus of humans and animals, especially under emergency conditions. The present invention further relates to such a device to facilitate rapid, gentle, blind oral intubation of the larynx or esophagus for purposes of ventilation, suctioning, inspection with a fiberoptic endoscope, forceps retrieval of foreign bodies, or remote biopsy, as desired.
II. Description of the Prior Art
As is well known, breathing and swallowing are accomplished through respective canals which open at the back of throat (the pharynx). One such canal extends through the larynx and trachea to the lungs to allow breathing. The other canal extends through the esophagus to the stomach for passage of food. The openings to the larynx and esophagus are positioned very close together. That positioning, along with other closely adjacent anatomical spaces at the back of the throat, presents difficulties to a medical provider needing to obtain rapid, specific access to a selected one of the canals, particularly in emergency situations.
For example, when a patient stops breathing, it is imperative that effective ventilation be instituted as soon as possible. Ventilation is best accomplished by forcing air through an orotracheal tube inserted through the mouth and laryngeal opening and into the trachea. Current methods of orotracheal intubation, the process of inserting the tube, are frequently slow and difficult, and prone to life-threatening error. The considerable angle between the axes of the mouth and larynx, and the intervening presence of the tongue and epiglottis, make it impossible to see the larynx through the mouth without special positioning and instrumentation. Also, there is ample space around the larynx into which an orotracheal tube can be easily and unwittingly misdirected. Indeed, it is not uncommon for the tube to be accidently inserted into anatomical spaces surrounding the larynx, such as the closely adjacent esophagus, rather than the larynx. Similarly, it is sometimes necessary to introduce a suction catheter at or into the esophageal opening to evacuate vomitus from the throat prior to orotracheal intubation. But, such a catheter can be accidently inserted into the larynx and trachea instead.
Whether ventilation of the lungs or suctioning along the oroesophageal axis is desired, prior art devices and methods do not assure the exclusive passage of the tubular member into the intended orifice (of the larynx or esophagus). The major danger is that if the tubular member is incorrectly placed, attempts to ventilate or suction the patient may instead result in suffocation. In a non-breathing patient, for example, if ventilation is supplied to the stomach rather than to the lungs through an orotracheal tube which has been accidentally introduced into the esophagus instead of the trachea, the stomach will inflate while the lungs receive no air and the patient will suffocate. Similarly, if suction is applied to a catheter which has been accidentally introduced into the trachea instead of the esophagus, the air in the trachea and lungs will be evacuated and the patient will suffocate. Thus, there is a need for an accurate means to direct tubes rapidly and selectively into the intended openings of either the larynx or esophagus.
One known method of guiding an orotracheal tube involves inserting a finger into the patient's throat and, using the sensation of touch, guiding the orotracheal tube down into the laryngeal opening. This is a "blind" method, in that the medical provider does not see the larynx when placing the tube. However, this blind, tactile method of intubation is not favored, and often results in accidental intubation of the esophagus instead of the trachea, frequently with tragic consequences. An instrument-guided method of blind intubation was developed in France by Leroy in 1827. But Leroy's two-bladed intubation speculum lacked any means to prevent accidental intubation of the esophagus or other areas adjacent to the larynx.
In 1912, a non-blind method of orotracheal intubation was developed using a blade laryngoscope to expose the larynx and allow the intubationist to "see" where to insert the orotracheal tube. This non-blind (or "visual") laryngoscopic method of orotracheal intubation was quickly accepted by the medical community as a logical way to eliminate the errors and complications inherent in blind intubation, and has become the method of choice for orotracheal intubation in the emergency setting.
Unfortunately, laryngoscopic orotracheal intubation has not only failed to eliminate accidental misintubation, but has introduced its own set of serious limitations and complications, sometimes catastrophic. For example, blade laryngoscopes, the devices used most for emergency orotracheal intubation, nearly always require that the laryngoscopist be positioned above the head of the patient to be intubated, and that the patient be lying in a supine position with mouth opened widely and neck extended so as to straighten the oral-pharyngeal-laryngeal axis in order to permit a transoral view of the larynx so that a tube may be inserted thereinto. But such relative positioning of the patient and laryngoscopist is frequently unachievable, where for example, the patient is trapped in an awkward position such as inside a wrecked vehicle. Similarly, the patient's mouth may not be widely openable where, for example, the temporomandibular joint is ankylosed or the jaw is broken; and extending the patient's neck may cause or aggravate a cervical spine injury. Another problem with laryngoscopic intubation is that substantial force must be applied via the rigid blade of the laryngoscope to depress the tongue and pull the epiglottis forward far enough to obtain a view of the larynx. This force frequently results in teeth being broken by the laryngoscope blade, and occasionally results in bleeding in the throat. Such bleeding can be uncontrollable in patients with thrombocytopenia or other bleeding disorders, and can prevent an adequate view of the larynx, thus hindering the attempt to intubate. A further problem is that during laryngoscopic intubation, there is no satisfactory way to prevent vomitus from rising from the esophagus into the throat, where it can obscure a view of the larynx, impairing the attempt to intubate, and where it can also be aspirated into the trachea and lungs, causing aspiration pneumonia and impairing effective ventilation. The presence of substantial blood, vomitus, or other debris in the throat currently requires that a suction catheter be introduced into the throat to evacuate these larynx-obscuring substances. But pausing to suction the throat delays intubation, since the suction catheter itself frequently obscures the view through the laryngoscope and interferes with manipulation of the orotracheal tube in the throat. Thus, orotracheal intubation cannot proceed easily and safely until the suction catheter is removed from the throat--at which time, further bleeding or vomiting may necessitate its reintroduction.
Another problem is that the technique of laryngoscopic intubation requires considerable training, skill, and experience before a high rate of success can be expected. One or more assistants are frequently needed by the laryngoscopist to perform ancillary tasks such as holding the patient's neck in an extended position, pressing externally on the larynx, and suctioning the throat. A further problem is that metal laryngoscopes are relatively expensive to buy and maintain. Perhaps the greatest imperfection of blade laryngoscopes is that they do not assure accurate orotracheal intubation. Even the laryngoscopes which substitute long, flexible or malleable fiberoptic image guides for rigid blades have major disadvantages. For example, they are very expensive, fragile, difficult to learn to use, slow in actual use, frequently require the use of an assistant, and have no reliable way to rapidly achieve correct and stable orolaryngeal positioning of their distal tips. Several attempts have been made to supersede the laryngoscope with devices which purport to facilitate blind intubation. But these devices have never overcome the principal problem of Leroy's device and of blade laryngoscopes, in that they have provided no safe and effective means to assure accurate orotracheal intubation.
For example, the intubation device shown in U.S. Pat. No. 4,832,020 includes structure to abut the front of the epiglottis to prevent the device from being inserted too far into the throat. However, there is no assurance of accurate and stable alignment of that device with respect to the laryngeal opening to be sure the orotracheal tube will be properly guided into the larynx. Moreover, that device requires tension to be blindly applied to the tongue, hyoid bone, hyo-epiglottic ligament, and epiglottis to pull these structures forward in order to achieve exposure of the glottis sufficient for intubation to be performed. But, with that device, too little or too much force could be applied, resulting in misalignment or misintubation.